1. Field of the Invention
This invention concerns composite closed-end vessels, and their production by backward extrusion.
2. Discussion of Prior Art
The technique of backward extrusion involves the use of a generally cylindrical container with parallel side walls, and a ram to enter the container dimensioned to leave a gap between itself and the side walls equal to the desired thickness of the extrudate. An extrusion billet is positioned in the container. The ram is driven into a forward face of the billet and effects extrusion of the desired hollow body in a backwards direction. The forward motion of the ram stops at a distance from the bottom of the container equal to the desired thickness of the base of the extruded hollow body. Extrusion speed, the speed at which the extrudate exits from the container, is not critical but is typically in the range 50-500 cm/min. Lubrication can substantially reduce the extrusion pressure required.